Mobile communication devices are a source of huge miniaturization pressure on electronic components. This especially concerns MEMS components (Micro-Electro-Mechanical System) such as microphones, for example, which have a relatively high structural form, with the consequence of restrictions for the device design particularly of mobile communication devices.
A wide variety of microelectronic components such as individual semiconductors, memories, processors, SAW components (Surface acoustic wave), BAW components (Bulk acoustic wave), and others, are fabricated at the wafer level. In this case, processes such as layer deposition, photolithography methods, printing methods and others are carried out in parallel for a multiplicity of components. In this case, a multiplicity of chips of identical type arise on a wafer. For encapsulating the components, external packages are often used.
Specifically for semiconductor components, usually on the basis of silicon wafers, numerous concepts have already been developed for a so-called WLP (wafer level packaging). In this method, the encapsulation is realized at the wafer level in a surface process. The majority of the WLP concepts known for semiconductor components are based on bump connections consisting of solder that is applied on the wafer by vapor deposition, printing or electrodeposition. A further wafer, as covering, is placed onto the bump connections. For this purpose, on account of the good thermomechanical matching, the same material is preferably used, such as, e.g., a further silicon wafer. It is also known to emplace a second wafer directly and to produce the electrical connection through the second wafer by means of through-plating through the first or second wafer.
However, a further wafer composed of silicon is costly and the required alignment and connection methods are likewise complicated and expensive. Moreover, during singulation, a larger material thickness has to be severed and, depending on the connection method, an additional material such as adhesive, solder, glass frit, etc., is also needed. This makes processing more difficult. Furthermore, the component has a significantly higher structural form.
Since, in many cases, still further packaging is effected anyway in addition to this primary encapsulation, such a WLP often constitutes an exaggerated outlay for achieving the aims.